Polytetrafluoroethylene resin produced by the aqueous dispersion polymerization method is coagulated from the resulting polymerization dispersion medium. It is commonly called "fine powder" resin to distinguish it from the polytetrafluoroethylene resin produced by suspension polymerization (called "granular" resin).
The fine powder resins fibrillate when subjected to shearing during paste extrusion (as described in U.S. Pats. Nos. 2,685,707 and 3,315,020) and during stretching at temperatures below that at which polytetrafluoroethylene sinters, 340.degree. C. (as described in U.S. Pat. No. 3,664,915 and Belgian Pat. No. 767,423).
A process is needed for producing a resin mode by the aqueous dispersion polymerization method which fibrillates in a manner that allows an increased degree of stretching. Such resin is desirable for many applications since the porosity of the finished article is increased and since less resin is needed for the article. This invention provides a process for obtaining such a resin.